A Brief History of the Observatory

The first astronomical observatory of Florence was the "Specola" of  The Imperial - Royal Museum of Physics and Natural History, built at the end of the XIX century by the Grand Duke of Tuscany Pietro Leopoldo of Lorraine. Soon after the "Specola" was built, the astronomers realised that its building was not well suited for observations (because of the increasing pollution from public ligths and of the  little stability and space within the observatory's tower - the "Torrino"). Because of these problems, Giovan Battista Donati (director since the end of 1859) made all necessary steps to build a new observatory.

 Giovan Battista Donati (1826-1873) founder of the Arcetri Observatory (left) and Wilhelm Tempel (1821-1889; right)

The new Observatory, designed to host the largest refractor available in Italy - the Amici telescope - was inaugurated on October 27, 1872. The location, the hill of Arcetri, besides being better for observations, had a deeper symbolic meaning. Not far from the Observatory, is the villa "Il Gioiello" (The Jewel), the final place of residence of Galileo Galilei.

Inauguration of the Observatory, 27/10/1872 (courtesy of the Biblioteca Nacional do Brasil).

A short time after the inauguration of the Observatory, Donati died. He caught cholera during a meteorology congress in Wien. The directorship was left vacant for many years, while the Observatory was entrusted to the German astronomer Wilhelm Tempel. Tempel's name remains linked to the drawings of nebulae, which are still preserved in Arcetri and which won him the Royal Prize at the Academy of Lincei for 1879. Of not less importance was his search for new nebulae with the Amici telescope. This lonely work was conducted in a building that was deteriorating rapidly due to serious construction problems.

Galaxy NGC 891 observed with the Amici telescope (drawing by W. Tempel) and with the Large Binocular Telescope.

After the death of Tempel (1889), the building was reconstructed. In 1894, a new Director was appointed, an astronomer from Padua, Antonio Abetti (1846-1928). He represents a turning point in the history of the Observatory. Antonio Abetti deserves the credit for having a new equatorial mount built for the Amici telescope. He, also, bought the "piccolo meridiano", a small meridian telescope mounted in such a way that it rotated around an East-West axis. Furthermore, he had sensed that the world of astronomy was changing not only due to with the advent of "new technologies of the time" such as photography and new telescopes but, also, due to the increasing international collaborations.

Antonio Abetti (1846-1928; left) e Giorgio Abetti (1882-1982; right)

Nevertheless, it was Giorgio Abetti, above all, who gave Arcetri a lasting international significance. In 1921, he succeeded his father as Director of the Observatory. In 1913, he participated in the geo-astronomical expedition led by Filippo De Filippi to Karakorum with the qualification of astronomer, geodesist and geophysicist. Crucial for Abetti's scientific training was his first trip to the United States, made in 1908, where he met George Ellery Hale. The American astronomer was pivotal for the scientific education of the younger Abetti. Their close and fruitful collaboration led to the construction of the 25 m. high solar tower. in Arcetri, modeled after the one on Mount Wilson in the United States.

Arcetri's solar tower, one of the first in Europe, was inaugurated on June 22, 1925 and has been used, almost continuously, until 1972. More than twelve thousand images of the Sun bear witness to the observational activities conducted at the tower by Abetti and his assistants. In 1923, a law was passed making all astronomical observatories autonomous institutions; however, the Arcetri Observatory would be considered one only in January 1926.

With Giorgio Abetti, a real Florentine "school" was born : Attilio Colacevich, Guglielmo Righini, Mario Girolamo Fracastoro and Margherita Hack were his pupils; and, beginning in the thirties, the scientific activity experienced a wide development, especially in the field of Solar Physics. In 1952, the year of the expedition to Sudan for the total solar eclipse, Giorgio Abetti managed to get the VIII International Astronomical Union meeting to take place in Rome, 30 years after the first. That same year, he gave up his teaching position and directorship of the Observatory.

Guglielmo Righini would succeed Abetti from 1953 to 1978, the year of his death. Righini dedicated himself, above all, to the study of new methods of investigation of the solar corona, especially, by introducing radio astronomy, whose complex technologies Righini had studied at Cambridge. Righini, also, would organize observational expeditions of eclipses using aircrafts in flight: this allowed for the artificial prolongation of the duration of the whole event by flying in the cone of the Moon's shadow.

Guglielmo Righini did not hesitate to enter the Arcetri Observatory into the European project JOSO (Joint Organization for Solar Observations). The aim of the project was to identify excellent astronomical sites in which to make new solar observatories; furthermore, he subscribed to the international effort that coordinated the solar observations so as to establish a network that can monitor the Sun 24 hours.

In 1978, the Observatory's direction was entrusted to Franco Pacini. He broadened further the scientific interests of the Observatory, both in galactic and extragalactic research and in advanced astronomical technologies; thereby, giving Arcetri a leading role in the area of international astronomical research.

Guglielmo Righini (1908-1978; left) e Franco Pacini (1939-2012; right)

Since 2002 the Arcetri Astrophysical Observatory is part of the National Institute for Astrophysics (INAF). The directors after Pacini were: Marco Salvati (2001-2005), Francesco Palla (2005-2011).

The last three directors: Francesco Palla, Filippo Mannucci e Marco Salvati.

The current director is Filippo Mannucci.